Alarm timepiece

ABSTRACT

A small alarm timepiece having a timepiece movement, an electrically operating buzzer as an acoustic alarm signal delivery means, a battery detachably mounted on the timepiece movement for energizing said buzzer for its operation, and an alarm switch for on-off control of the operation of the buzzer. This alarm switch is operatively connected with the movement so as to be closed at a preset time point and to remain closed for a certain predetermined operation period. The drive circuit for the buzzer is designed as a free-running oscillator having an oscillator transistor. In addition to the alarm switch, there is provided a switching transistor operatively connected with the first mentioned transistor. There is provided a CR-time limiting circuit operatively connected with the switching transistor for control thereof. In this way, the operating period of the buzzer is limited to only a small fraction of the closure period of the alarm switch which is adapted for being mechanically closed at the preset time by the action of an alarm control mechanism fitted to the timepiece movement. In this way, the power consumption of the electronic alarm can be minimized.

United States Patent [1 1 Yoshida 51 Dec. 25, 1973 1 ALARM TIMEPIECE[75] Inventor: Makoto Yoshida, Tokorozawa,

Japan 22 Filed: May2i, 1972 211 A 1.No.=2ss,s1b

[30] Foreign Application Priority Data June 5, 1971 Japan 46/47337 [52]US. Cl. 58/38, 58/575 [51] Int. Cl. G040 21/34, G04b 23/12 [58] Field ofSearch 58/38, 57.5

[ 5 6 References Cited UNITED STATES PATENTS 3,638,418 2/1972 Spadini58/57.5 3,462,943 8/1969 Spadini 58/575 3,505,806 4/1970 Schwiegne etal. 58/38 3,577,876 5/1971 Spadini 53/575 3,589,123 6/1971 Flaig et al.58/38 3,689,919 9/1972 Ganter et al r. 58/38 X Primary Examiner-GerirgeH. Miller, Jr. Attorney-John C. Holman et al.

57 ABSTRACT A small alarm timepiece having a timepiece movement, anelectrically operating buzzer as an acoustic alarm signal deliverymeans, a battery detachably mounted on the timepiece movement forenergizing said buzzer for its operation, and an alarm switch for on-offcontrol of the operation of the buzzer. This alarm switch is operativelyconnected with the movement so as to be closed at a preset time pointand to remain closed for a certain predetermined operation period. Thedrive circuit for the buzzer is designed as a free-running oscillatorhaving an oscillator transistor, In addition to the alarm switch, thereis provided a switching transistor operatively connected with the firstmentioned transistor. There is provided a CR- time limiting circuitoperatively connected with the switching transistor for control thereof.In this way, the operating period of the buzzer is limited to only asmall fraction of the closure period of the alarm switch which isadapted for being mechanically closed at the preset time by the actionof an alarm control mechanism fitted to the timepiece movement. ln thisway, the power consumption of the electronic alarm can be minimized.

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, 1 ALARM TIMEPIECE This invention relates toimprovements in andrelating to a small electronic timepiece, especially an electronicwatch, which is fitted with an electronically driven alarm from batterymeans contained in said watch and adapted to drive the electronicallyoperatable watch movement.

In the case of a mechanical watch, having its mechanical power source,such as power spring or the like and fitted with an alarm of themechanical driven type, the power spring must be energized each time adesired alarm time is to be established, so as to replenish in advancethe power consumption to be made during the alarm period. This is causedby the fact that the conventional power spring has a relatively smallpower capacity which is naturally of most concern on the one hand, andon the other hand the alarm mechanism will operate, each time the alarmis sounded, for a relatively long period, such as ten minutes or evenlonger until it is brought to a dead stop, Thus, when a user of thealarm watch does not manipulate a certain stop means for stopping theworking of the once operated alarm, the alarming operation may continueuntil the power spring has been brought to its completely rewound state.This period may generally xtend only for five minutes or so.

With modern development of electronics as applied rapidly to and in thefield of timepiece movement engineering, it is known to a skilled personin the art to employ-a battery as the power source of a watch alarm forobviating the troublesome alarm energy replenishment necessary each timethat the alarm time setting job is performed. It is, however, highlydesirable to control the electrical alarm switch adapted for on-offcontrol of the electrically driven alarm mechanism by a wheel meanswhich rotates once per 12 or 24 hours on account of its highlysimple'structure and easy setting convenience as commonly provided byuse of the conventional alarm mechanisms. If the electric alarm shouldoperate for as long as 10 minutes or so, with the electric switch meanskept in its continued conducting state, the power battery would beconsumed within a relatively short period which must naturally beavoided from the view point of power economy.

The main reason why the electronic watch fitted with an electronic alarmhas no't'yet been commercialized resides in the aforementioned drawback.For instance,

when the electronic alarm, such as electronic buuer,

is brought into operation once per 12 or 24 hours for 10 minutes or sowithout manipulation of the alarm stop means, the power battery must bereplaced by a new one within a half yearior so. When the timepiecemovement is of the electronically driven type and the power battery iscommon to both, the durable life of the battery may be still furthershortened to, for instance, 5 months or so. When the alarm has beendesigned to provide for settability to several destined alarm timepoints, the aforementioned drawback has made it difficult to realize thelast mentioned alarm mechanism advanced so far.

An object of the present invention is to provide an electronicallyoperated alarm mechanism devoid of the, aforementioned conventionaldrawbacks and highly adapted for use in a small timepiece, especially anelectronic watch, which is small in its design and arrangement, andcapable of usage for an extended time period without exchange of thepower battery.

For the realization of the aforementioned object of the invention, theinvention starts in its broadest aspect from such a combination of: atimepiece movement; an acoustic alarm means arranged to be driventhrough an electronic drive circuit means from a battery means; and oneor more alarm switches adapted for bringing said drive circuit meansinto operating conditions at least at a certain predetermined time. Thecharacterizing feature of the present invention resides broadly in suchthat the said drive circuit for the drive of the acoustic alarm meanscomprises in combination a freerunning transistored oscillator whichincludes a oscillator transistor and a switching transistor electricallyconnected to the base electrode thereof, and a CR-time limiting circuitoperatively connected with said switching transistor for control of theoperation thereof.

In such a device, when the alarm switch is turned on, then the switchingtransistor is turned on or off, as the case may be, upon lapse of apredetermined time period as determined by the time constant of theCR-time limiting circuit. With the operational conversion of theswitching transistor from on to off or in the reverse direction in theabove sense, the oscillator circuit is deprived of theoperationalcurrent and a small amount of dark current will continue toflow through the transistor until the alarm switch or switches has beenturned off. At this instance, the acoustic alarm terminates itsoperation. Therefore, it will be seen that the power consumption fromthe instance where the operational termination of the acoustic alarm hastaken place to the point where the alarm switch turns off may beneglegibly small and thus highly economical.

These and further objects, features and advantages of the invention willbecome more apparent when the following detailed description of theinvention is read with reference to the accompanying drawingsillustrative of several preferred embodiments of the invention.

In the drawings:

FIG. 1 is an axial section of a small timepiece fitted with anelectronic alarm device embodying the principles of the inventionwherein, however, the drive circuit block for the acoustic alarm issectioned only partially and the regular gear train and the batteryblock contained in the movement are shown in their elevation.

FIG. 2 is a bottom view of the timepiece movement shown in FIG. 1,showing, however, substantially exclusively the alarm mechanism, otherrelated conventional parts having been omitted from the drawing forbetter and more clear understanding of the invention.

FIG. 3 is a plan view of the timepiece movement shown in FIGS. 1 and 2,yet being shown on a somewhat reduced scale relative to that employed inFIGS. 1 and 2, wherein, however, several minor and conventional partsare not shown only for simplicity of the drawing.

FIG. 4 is a connection diagram of an embodiment of the device circuitfor the acoustic alarm employed in the invention.

Referring now to FIGS. 1-4, the first embodiment will be describedhereinbelow in detail.

Numeral 1 generally denotes a watch movement in its broadest sense andcomprises a conventional pillar plate 2, appearing only partially andmounting several main working parts, as will become more clear as thedescription proceeds.

Numeral 3 represents a mercury battery of known structure and detachablymounted within said movement 1. In the present'embodiment, this battery3 is adapted to feed an electronically operated timepiece movement and abuzzer with current, as will be more specifically described hereinafter.

A battery mount 4 made of an insulating material and fixed with saidpillar plate 2 mounts the battery block 3 in position, a pressure spring5 detachably attached by means of set screws 5a and.5b to the plate 2holding the battery block in position from upper of FIG. 1 with a slightresilient pressure applied thereto.

Numeral 6 represents only schematically an electronic drive circuit ofconventional structure and molded into a block with a synthetic resinand detachably attached to pillar plate 2 by means of set screws 6a, 6band 60. This drive circuit is adapted for driving electro-dynamically aconventional time base oscillator, preferably in the form of a balancewheel motor, a turning fork, a turning lead or the like, as commonlyknown per se. The drive circuit is electrically connected through theplate 2 and lead wire means, not shown, to the battery 3, as known perse.

Numeral 8 represents a main working parts block including theconventional watch gear train and comprising a balance wheel 8a which isdriven electromagnetically from said electronic drive circuit 6, saidgear train, although not shown specifically by virtue of its verypopularity, being mounted by and between the plate 2 and bridges 8e;8fwhich are fixedly attached thereto by means of a plurality of set screws8b;8c and 8d. It should be mentioned at this stage that the term block"in this case is used only for convenience so as to discriminate the geartrainas a whole from other working parts of the watch and it does notconstitute a practical block.

Numeral 9 represents an alarm oscillator circuit block comprisingtransistor(s), condenser(s), resistors and the like which constitute anelectronic oscillator and compacted into a molded block 9a by asynthetic resin such as an epoxy base resin, and a transformer 9belectrically connected with said oscillator and with a piezoelectric orelectro-strictive element 25. This transformer 9b serves for elevatingthe output from the oscillator in its voltage so asto adapt foroscillation of theelement 25 as will become more apparent as thedescription proceeds. This circuit block 9 is fixedly, yet easilydetachably attached to the plate 2 by means of several set screws 9c;9d.

Numeral 10 denotes a conventional time-indicating dial bearing on itsouter surface with known timeindicating symbols although not shown, forthe demonstration of time by cooperation with time-indicating hands l4,l5 and 16. This dial 10 is detachably mounted on the plate 2, althoughthe attaching means have been omitted from the drawing only forsimplicity and convenience. It should be noted, however, that aconductive strip 10a is provided in a concentric ring on the insidesurface of the dial 10, and preferably, by the print circuit technique.

Battery mount plate 4 is formed with a perforation 4b in which aU-shaped contact spring 4a is kept in position in somewhat projectingmanner. In the assembled position shown, this contact spring 4a servesas conducting means between said battery 3 and conductive strip 10a.

Numeral 11 denotes a conventional cannon wheel and a conventionalunlocking wheel 12 is rotatably mounted thereon. An unlocking spring 13is provided as shown, especially in FIGS. 1 and 2, the root end of thisspring 13 is fixedly mounted on a terminal 92 of said oscillator circuitblock 9 by means of a set screw 13a. The free end 13b of spring 13 iskept in pressure contact with the upper surface of the wheel 11, so asto urge resiliently the latter to move axially downwards when seen inFIG. 1. A projection or contact portion 13c is formed on the spring 13at an intermediate point between the ends thereof, thus providing apossibility to establish an electrical cooperation with conductive strip10a on the dial 10'.

Cannon wheel 11 is formed with three projections 11a having mutuallydifferent radial lengths measured from the center of the wheel 11. Onlyfor simplicity, however, these projections llaare represented as if theyare single in FIG. 1. In a corresponding way, unlocking wheel 12 isformed with three different perforations 12a (refer especially FIG. 2).

Numerals 40, 41 and 42 represent a series of successively engagingintermediate gears of which the last one 42 is directly attached to theinnermost end of an unlocking stem 43. This stem 43 is manuallyrotatable as in the conventional winding stem 45 only partially shown,these stems 43 and 45 being mounted rotatably in the pillar plate 2,although the bearing means have been omitted from the drawing by theirvery popularity. As seen from FIG. 2, manual torque can be transmittedfrom the unlocking stern applied occasionally thereto, through gears 42,41 and 40 to unlocking wheel 12 for setting the latter to a desiredalarm time. For indication of the alarm time, the unlocking wheel 12 isfitted with an alarm hand 14. This hand 14 is press-fit on the boss ofthe wheel 12.

Numeral 44 represents an intermediate gear which is designed andarranged to transmit driving torque from the regular time-keeping geartrain to the cannon wheel 11. As commonly known, the cannon wheel 11performs a complete revolution per 12 hours by receiving motion from thegear train of the watch. When the alarm time comes, the projections 11aon the wheel 11 are brought into engagement with corresponding andmating perforations 12a on the wheel 12, thereby the former wheel 11being urged to move downwards in FIG. 1 and nearer towards the latterwheel 12, so as to establish an electrical connection between thecontact portion on spring contact 13 and the conductive strip 10a ondial 10.

Hour hand 15 is press-fit on the boss of cannon wheel 11 asconventionally. Minute hand 16 is attached on top of a conventionalcannon pinion 17.

Numeral 18 represents a case central body which mounts detachably atransparent plastic cover 19 used in this specific embodiment in placeof a crystal, a ringshaped tension spring 19a urging the cover frominside to expand resiliently outwards, so as to establish a tight andsealed connection between the cover and the case center body.

A ring-shaped movement positioner 20 is positioned along its substantialperipheral length between plate 2 and case center body 18. A sealingring 21 is inserted between the case central body 18, and a membranecarrier 22 having a ring web projection 220 on which the periphery of anoscillatory membrane 24 is fixedly attached by means of adhesive. Thecarrier 22 is formed with an inwardly projecting arm 22b and providedwith an insulator sleeve 23a which holds firmly a combined stationarycontact and terminals 23. On the inside surface of the membrane 24, apiezoelectric or electro-strictive element 25 is firmly attached byglueing or the like conventional attaching means, conductive leads 26connecting electrically the contact and terminals 23 with the element25.

The molded alarm oscillator circuit block 9 is provided at its outputside with conductive spring arms 9f which are normally kept in pressureand conductive contact with the members 23 when the block 9 and membranecarrier 22 have been assembled together in position as seen clearly fromFIG. 1. The root ends of said spring arms 9f are embedded rigidly in themass of the molded block 9.

Numeral 27 denotes a back cover which is formed with .a number ofprojections 27a over its substantially whole area so as to prevent atight contact with the wearers skin, while the remaining base area 27bis formed with a number of perforations 27c for releasing acousticalarming signals from inside of the watch into the open atmosphere.

At the outside periphery, the back cover 27 is formed with severalrecesses 27d for receiving operating ends of a turning tool. Further,the back cover 27 is formed on its peripheral surface with male screwthreads 27e adapted for engagement with mating female screw threads 180formed on the case central body 18. For attachment of the back cover 27,it is screwed from upper into the body 18 by use of the turning tool.

It will be clear from the foregoing that the interior space of the watchas defined by membrane 24, carrier 22 thereof, sealing ring 21, casecentral body 18 and transparent and plastic front cover 19 is kepteffectively in a sealed condition for prevention of an invasion ofmoisture from outside into inside of the watch.

In FIG. 4, an embodiment of the drive circuit for the drive of a buzzer50, said circuit basically comprises a membrane 24 and a piezoelectricor electro-stritive element 25.

Numeral 51 represents an alarm switch comprising unlocking spring 13 andconductive strip a which are specifically shown in FIG; 1.

Blocking oscillator transistor 52, switching transistor 53 adapted foron-off control of the operation of the former transistor 52 and timertransistor 54 adapted for on-off control of the operation of the lattertransistor 53 so as to determine the operational duration period ofbuzzer 50, are seen in FIG. 4 and connected one after another as shown.

The base electrode of the transistor 54 is connected through sourceconductor 55 to the positive side of a source battery 64, on the onehand, said source conductor 55 being inserted with resistor 56 and alarmswitch 51, while said base electrode is connected to earth through acondenser 57. Resistor 56 and condenser 57 constitute in combination atime-limiting circuit which operates in such way that with theelectrical charge accumulated in the condenser 57, the base potential oftransistor 54 will vary. The collector electrode of said transistor 54is connected through collector resistor 58 to source conductor and atthe same time directly coupled with the base electrode of switchingtransistor 53. The emitter electrode of transistor 54 is directlyearthed. The collector electrode of switching transistor 53 is connectedthrough resistor 60 to source conductor 55, while the emitter electrodeof the same is connected to earth through condenser 62, and at the sametime with one end of the primary winding of a blocking oscillatortransformer 63, the opposite end of said winding being connected withthe base electrode of transistor 52.

The collector electrode of transistor 52 is connected with one end ofsecondary winding of said transformer 63, while the emitter electrode ofthe same transistor is connected directly to earth.

A central tap on the secondary winding of the transformer 63 isconnected to source conductor 55, while the buzzer 50 is connectedacross the secondary winding. The transformer 63 acts as a voltagebooster, so as to drive the element 25 optimumly. As seen, resistor 60,condenser 62, transformer 63 and transistor 52 constitute in combinationa blocking oscillator circuit shown by a dotted-chain line block 65.Circuit elements 56, 57, 58 and 54 constitute in combination aCR-time-limiting circuit shown by a chain-dotted line block 66.

The operation of the firstembodiment of the watch alarm according to thefirst embodiment of the present invention will be described in detail.

The unlocking wheel 12 is set to a certain selected time point bymainpulating the auxiliary winding stem 13 as was briefly describedhereinbefore.

When the alarming time comes, projections 11a on the wheel llare broughtinto engagement with corresponding perforations 12a in the wheel 12 sothat the former wheel 11 is urged to move downwards in FIG. 1 under theaction of unlocking spring 13 and the intermediate contact portion l3cthereof is brought into pressure contact with the conductive strip 10a,thereby the unlocking switch 51 being turned to on. In this way, currentis supplied from battery 3 to alarm oscillator circuit 9. Morespecifically, a circuit is closed through battery 3, contact spring 4a,conductive strip 10a on dial 10, unlocking spring 13, oscillator circuit9 and pillar plate 2.

When the oscillator circuit 9 starts to oscillate in this way at .acertain constant frequency, preferably selected between 1,000 and 4,000cycles per second, the oscillatory output voltage therefrom is conveyedthrough the elevating transformer 9b to the element 25 which is thuskept in oscillation together with its carrying membrane 24. By theoscillative movement of the membrane 24, a corresponding acoustic signalis generated and will be delivered from the interior of the watch casingcomprising the members l8, l9 and 27 into the open atmosphere throughthe perforations 27c of the back cover 27.

At this stage, the circuit shown in FIG. 4 will act in the followingway.

When the alarm switch 51 turns on in the aforementioned way, the basepotential at the transistor 54 will rise up in accordance with the timeconstant as determined by the specifically selected combination ofresistor 56 and condenser 57. During this potential rising-up perioduntil the base voltage attains at the conducting voltage for thetransistor 54, the latter is held in its offcondition.

During this period, the collector voltage at transistor 54 is keptsubstantially at the source voltage level, thereby providing a properbase current to transistor 53 for operation thereof. Thus, thetransistor 53 is in its conducting state and thus provides through itscollector a base current to transistor 52. At this stage, the impedanceat the collector-emitter passage becomes naturally enough lowpractically to establish the blocking oscillator 65. In this way, thebuzzer 50 operates to deliver acoustic alarm signal.

Upon lapse of a certain predetermined time period as determined by thetime constant provided by the specifically selected combination ofresistor 56 and condenser 57, the base potential of transistor 54reaches its threshold voltage, thus the transistor becoming on, whilethe collector electrode thereof has substantially nil potential. Sinceat this stage, the base potential of transistor 53 becomes substantiallynil, it becomes off. Therefore, the blocking oscillator can notoscillate and the operation of buzzer 50 will cease.

In this way, the buzzer'50 will continue to operate for a predeterminedperiod depending upon the CR-time constant as determined by thecombination of resistor 56 and condenser 57, as referred tohereinbefore, upon the closure of alarm switch 51, and then itterminates its operation automatically.

Upon the cease of operation of the buzzer 50, the transistor 54 onlywill be kept in its operating condition until the alarm switch 51 isopened. But, the current consumption during this stage can be madenegligibly small by selecting the resistances at resistors 56 and 58 torelatively large values.

In a preferred practical embodiment, the main circuit constants areselected as'follows:

resistor 56 5 megohms;

resistor 58 l megohm;

resistor 60 I kiloohms;

condenser 57 l microfarad;

condenser 62 l nanofarad;

winding ratio of transformer 63 l0; duration term of operation ofbuzzer'50 about seconds; operating frequency of blocking oscillator 65LOGO-4,000 Hz;

The above specified duration time, about 5 seconds, buzzer 50 is enoughfor the desired alarming purpose, which is naturally very short incomparison with the regularly employed conventional value such asminutes. In this specific embodiment, the current consumption uponautomatic cease of buzzer operation amounts to 2-3 microamperes which isvery small in comparison with that for the buzzer operation, amountinggenerally to l-2 miliamperes.

When considering such case that the timepiece movement is of theelectronically driven type and thus, the source battery is designed andarranged to be common to the movement and the alarm, the daily powerconsumption rate will amount at the highest to 7 microampere-hours underthe assumption that the buzzer operates twice per day. When furtherassuming that the electronic movement operates with 8 microamperes, thenthe daily power consumption will amount to 0.192 miliampere-hours and ifthe capacity of the source battery be 100 miliampere-hours, then theoverall life of the battery used for the said both purposes will be:

100/ 0.007 0.192) E 500 days.

Thus, the electronic timepiece with the electronic alarm built inaccordance with the present invention will operate for 500 days.

On the other hand, when the electronic watch is designed to operate. fora complete year with the source battery having the same capacity asabove, how many times, the electronic alarm can operate per day? Since69 miliampere-hours must be consumed for the continuous operation of theelectronic movement for a complete year round, the remaining poweravailable for the operation of the alarm will be 30 miliamperehours.With the power consumption of the alarm being 3.5 microampere-hours foran alarming operation, 8 500 times of alarming operations can be assuredwith the above mentioned energy available therefor, and thus, the alarmcan operate 24 times per day which is sufficient for the destined alarmservice.

When further assuming that the alarm must continu' ously operate oncefor 10 minutes in place of 5 seconds and a current of 3 miliamperesshould flow during the prolonged service period, only times of alarmingoperation or so could be performed. Thus, in such case, alarmingoperation once per two or three days can only be assured and acommercially acceptable electronic alarm watch could not be provided.

In a modified arrangement shown in FIG. 5, the alarm switch equallydenoted with the same reference numeral 51 as before is shifted to aposition along the source conductor 55 which lies between the blockingoscillator 65 and the time-limiting circuit block 66.

For convenience and easy comparison, same reference numerals are usedfor same or similar circuit parts employed in the present modificationas those shown and described in and with reference to FIG. 4.

With the switch 51 closed, current will flow from battery source 64through source conductor 55, secondary winding of transformer 63 andcollector-emitter passage of transistor 52 to earth, for actuation ofthe buzzer 50 as in the aforementioned way. Since, at the present stage,the impedance between source line 55 and earth which provides the abovecurrent passage route, practically variable contact pressure at theswitch 51 when the latter is arranged as shown in FIG. 4 will affectappreciably the emitter-collector voltage of the same transistor, thusinfluencing the alarm signal delivered from the buzzer, generally in itsreducing sense. Thus, a certain affect upon the buzzer signal by thevariable contact at the switch 51 when it is arranged as shown in FIG. 4may frequently be encountered. In the modified arrangement shown in FIG.5, since the resistance values at resistors 56 and 58 have been selectedto have rather larger values and due to the modified positionalarrangement of the switch 51, almost any influence upon the timeconstant of the time- Iimiting circuit comprising several circuitelements 54, 56, 57 and 58 can not be encountered even by the variablecontact pressure at the switch 51.

In addition, the aforementioned drawback of varia' tion in the impedanceof the emitter-collector passage of the transistor 52, through which themain drive current for the actuation of the buzzer, can also beremedied.

In this way, the buzzer can operate in a highly stabilized way and at asubstantially constant signaling level.

In a still further modified arrangement of the buzzer drive circuitshown in FIG. 6, numerals 151; 153; 155; 156; 157; 163; 164 and 165 aresimilar to those denoted respectively with numerals 50; 51; 53; 55; 56;57; 63; 64 and 65 in the foregoing embodiments.

The alarm switch 151 provided in the source conductor 155 between biasresistor and transformer 163. This positional arrangement of the alarmswitch is for the same purpose as mentioned in the foregoing withreference to FlG. 5.

In the present modification, transistor 153 is so designed and arrangedthat it may take over the function of the timer transistor 54 inaddition to that of a switching transister. The base of this transistoris connected through resistor 156 to source conductor 155 and throughcondenser 157 to earth. The collector is connected through conductorllto the base of a transistor 171 which is positioned substantiallysimilarly to that'shown at 53 in FIG. 4 or 5. The emitter of transistor153 is directly earthed.

Transistor 171 constitutes in cooperation with a transistor 170, anastable or free-running multivibrator, having several auxiliary circuitelements 172; 173; 174; 175 and 176 which are connected one afteranother as shown.

When a predeterminedly set time point comes, alarm switch 151 is closedand either transistor 170 or 171 is turned on, while the remainder willbecome simultaneously off and vice versa, being performed as known perse in a repeated manner. This repeatedly performed on-off operation willextend for a certain predetermined period, as determined by specificallyselected circuit constants of the elements 172; 173; 174 and 175.

With the transistor 171 turned to on, current will flow through thetransformer 163, so as to drive the buzzer 150. r

For a certain short period upon closure of the alarm I switch 151, thebase potential at the transistor 153 will continue to rise up inaccordance with the specific time constant as determined by therespective values of re sistor 156 and condenser 157. During the termuntil attainment of the base potential at the conductive voltage oftransistor 153, the latter maintains its off state. Thus, although themultivibrator circuit 165 will continue to oscillate, the transistor153' turns on when the base voltage becomes equal to the conductivethereof.

Thus, currentwill flow through the resistor 174 and thecollector-emitter passage of transistor 153 and the base potential oftransistor 171 will decrease and this transistor will not become on.Therefore, the operation of the circuit 165 will cease.

Although current will continue to flow through resistor 156;base-emitter passage of transistor 153, and through resistor 175;base-emitter passage of transistor 170; and further through resistor176; and collectoremitter passage of transistor 170, the overall powerconsumption rate at this stage may be neglegibly small, by virtue of theresistance values at 156; 174; 175 and 176 selected to relatively smallvalues.

In the case of the modification shown in FIG. 6, main circuit elementshave been selected to have respective circuit constants as follows:

resistors 174 and 176 each 300 kiloohms;

resistor 175 100-300 kiloohms;

condensers 172 and 173 each 2,000 picofarads;

resistor 156 2 megohms;

condenser 157 2 microfarads;

With use of these constants, the working period of the buzzer extendsfor about 4 seconds. The oscillation frequency: l,O00-4,000 Hz;buzzer-operating current: about 2 miliamperes; Current consumption rateafter automatic cease of operation of the buzzer is about 1 microampere.

With use of a conventionally used battery, the alarm watch can operatelonger than one year, as was true in the foregoing embodiments, so faras the alarm is not too much frequently actuated.

if the alarm switch is kept in its astably contacting state, a so-calledchattering phenomenon will be invited. In such case, transistor 153 willunexpedly be turned from on to off. For avoiding this drawback,provision of a condenser shown with dotted lines at 177, for instance,of 10 microfarads, may preferably be made.

As was explained hereinbefore, about 7,0009,000 alarming operations canbe assured over a complete year round, or more specifically 20-30 timesof alarming operation per day, canbe assured, even with use of a mercurybattery of the normal capacity as is being used for the drive of theelectronic watch movement, and thus a highly convenient and efficientalarm watch can be provided when obeying the novel principles of theinvention, as was disclosed in the foregoing specification and to bespecifically claimed in the appended claims.

As a result, an advanced electronic alarm for small timepieces,especially electronic watches, where a plurality of alarming times arepreset at a time. In this case, a corresponding number of alarm switchesmust be proved as known per se. These switches are operatedsuccessively. Upon successive arrival of these preset time points, thebuzzer is operated in succession, as may be well supposed from theforegoing description.

The embodiments of the invention in which an exclusive property orprivilege is claimed are as follows:

1. In an alarm timepiece comprising a timepiece movement; acousticgenerating means mounted on said movement for generating an acousticalarm signal; an electronic drive circuit mounted on said movementandhaving a detachable battery for providing current to said drive circuit;at least one alarm switch operatively connected with said movement andsaid drive circuit so that upon closure of same at a preset time saidcurrent flows through said drive circuit to initiate operation of sameand cause said generating means to generate the acoustic alarm signal,the improvement wherein said generating means comprises a piezoelectricoscillator attached to a vibratable membrane mounted in said timepiece,said electronic drive circuit comprises a free-running oscillatorcircuit having an oscillator transistor; a switching transistoroperatively connected to said oscillator transistor; a time limitingcircuit operatively connected to said switching transistor, said timelimiting circuit having a timer transistor anda resistor and condenserproviding a time constant, so that when said alarm switch is closed saidacoustic generating means emits the acoustic alarm signal for a timeperiod determined by said time constant, and the time period of theacoustic alarm signal is limited to a small fraction of the totalclosure period of the alarm switch.

2. The alarm timepiece of claim 1, wherein said freerunning oscillatorcircuit is connected directly to said battery, while said time-limitingcircuit is connected through said alarm switch to said battery.

3. The alarm timepiece of claim 1, wherein said freerunning oscillatorcircuit is of the blocking type and connected between a capacitiveelement and a resistor element contained therein; the emitter electrodeof said switching transistor, which is connected with said capacitativeelement, is connected through the primary the electronic alarm to aminimum.

4. The alarm timepiece of claim 1, wherein said freerunning oscillatorcircuit is an astable multivibrator and said acoustic generating meansis adapted for being driven by coil means inserted in said oscillatorcircuit, the base electrode of the oscillator transistor beingelectrically connected with the collector electrode of the switchingtransistor, so as to reduce the power consumption of the electronicalarm to a minimum.

1. In an alarm timepiece comprising a timepiece movement; acoustic generating means mounted on said movement for generating an acoustic alarm signal; an electronic drive circuit mounted on said movement and having a detachable battery for providing current to said drive circuit; at least one alarm switch operatively connected with said movement and said drive circuit so that upon closure of same at a preset time said current flows through said drive circuit to initiate operation of same and cause said generating means to generate the acoustic alarm signal, the improvement wherein said generating means comprises a piezoelectric oscillator attached to a vibratable membrane mounted in said timepiece, said electronic drive circuit comprises a free-running oscillator circuit having an oscillator transistor; a switching transistor operatively connected to said oscillator transistor; a time limiting circuit operatively connected to said switching transistor, said time limiting circuit having a timer transistor and a resistor and condenser providing a time constant, so that when said alarm switch is closed said acoustic generating means emits the acoustic alarm signal for a time period determined by said time constant, and the time period of the acoustic alarm signal is limited to a small fraction of the total closure period of the alarm switch.
 2. The alarm timepiece of claim 1, wherein said free-running oscillator circuit is connected directly to said battery, while said time-limiting circuit is connected through said alarm switch to said battery.
 3. The alarm timepiece of claim 1, wherein said free-running oscillator circuit is of the Blocking type and connected between a capacitive element and a resistor element contained therein; the emitter electrode of said switching transistor, which is connected with said capacitative element, is connected through the primary winding of a transformer in said oscillator circuit, the secondary winding of which is at least partially connected operatively with said acoustic signal delivery means, with the base of the oscillator transistor, to thereby control said oscillator circuit with low current, and for interrupting the base current of said oscillator transistor substantially completely during the remaining closure period of the alarm switch which is devoid of the operational period of said acoustic signal delivery means so as to reduce the power consumption of the electronic alarm to a minimum.
 4. The alarm timepiece of claim 1, wherein said free-running oscillator circuit is an astable multivibrator and said acoustic generating means is adapted for being driven by coil means inserted in said oscillator circuit, the base electrode of the oscillator transistor being electrically connected with the collector electrode of the switching transistor, so as to reduce the power consumption of the electronic alarm to a minimum. 